if statement

From Cppreference

Conditionally executes code.

Used where code needs to be executed only is some condition is present.

[edit] Syntax

[edit] Explanation

expression shall be an expression, convertible to ​bool​.

If it evaluates to ​true​, control is passed to statement_true, statement_false (if present) is not executed.

Otherwise, control is passed to statement_false, statement_true is not executed.

[edit] Keywords

if, else

[edit] Example

The following code shows several usage cases of the if statement

​#include <iostream>
 
int main()
{
    int i = 2;
    if (i > 2) {
        std::cout << "first is true" << std::endl;
    } else {
        std::cout << "first is false" << std::endl;
    }
 
    i = 3;
    if (i == 3) std::cout << "i == 3" << std::endl;
 
    if (i != 3) std::cout << "i != 3" << std::endl;
    else        std::cout << "i != 3 is false" << std::endl;
 
    return 0;
}​

Output:

​first is false
i == 3
i != 3 is false​